EP 0 626 290 B1 discloses a vehicle seat of the type in question, with a substructure and a backrest which is attached in an articulated manner to the substructure, wherein the vehicle seat is transferable from a seat position into a floor position by folding the backrest forward, and a respective first rocker and a respective second rocker are provided on the two outer sides of the seat in order to couple the backrest to the substructure, wherein the substructure, the first rocker, the backrest and the second rocker as four gearing members which are connected to one another via joints define a four-bar linkage. This vehicle seat does not have a child seat fastening system which can be used independently of the vehicle belt system. Such child seat fastening systems are known, for example, by the name ISOFIX and, on the vehicle-seat side, comprise two lower attachment points which are arranged at a distance of 280 mm from each other in the transition region between seat cushion and seat back. Latch systems of the child seat fastening system, also referred to as connectors, are fastened to said two lower attachment points. The child seat fastening system optionally additionally comprises a third attachment point for fastening what is referred to as a top tether belt strap of the child seat. The child seat which is placed onto the vehicle seat is fastened to the ISOFIX attachment points without using the vehicle belt system. In particular, the permissible position of the attachment points of the ISOFIX system is standardized by the standard ISO 13216.
DE 101 56 644 C2 likewise discloses a vehicle seat with a four-bar-linkage attachment of a backrest to a substructure. However, a child seat fastening system is not provided for this vehicle seat, and therefore this vehicle seat is suitable only to a limited extend for transporting children, namely only in combination with child seats which can be used with the vehicle belt system.
DE 10 2004 004 376 B3 discloses a cross piece which receives a child seat fastening system and is fixably connected to the substructure of a vehicle seat via a lower part of a backrest fitting. Such an attachment cannot simply be transferred to vehicle seats which do not have a backrest fitting or the backrest fittings of which are located significantly above the attachment points of the child seat fastening system. This is frequently the case in vehicle seats, the backrest of which is attached in an articulated manner to a substructure via a four-bar linkage.
JP 2010 100 229 A discloses a transverse tube which runs between body work adapters of a backrest and on which attachment points of a child seat fastening system are provided.